Liquid fuel pumping apparatus

ABSTRACT

A liquid fuel pumping apparatus including a shuttle the excursion of which determines the maximum quantity of fuel which can be supplied to an engine, the extent of outward movement of the shuttle being omitted by a stop in the form of a piece having a contoured surface, the stop being mounted in a fluid pressure operable piston. The position of the piston depends upon the speed at which the apparatus is driven. In addition the setting of the piece is determined by axially movable member the axial position of which is determined by a diaphragm to which is applied air under pressure from the inlet manifold of the associated engine.

0 llnite States Patent [1 1 1111 3,726,263 Kemp Apr. 10, 1973 LIQUID FUEL PUMPING APPARATUS 2,869,529 l/ 1959 Oxenfart ..417/295 [76] Inventor: Kenneth Albert Walters p, 26a 3,219,020 11/1965 Roosa ..417/295 Castlebar Park London En land 3477'4l8 H969 "417,295 g 3,314,406 4/1967 Kemp ..417/295 [22] Filed: Mar. 15, 1971 Primary ExaminerLaurence M. Goodridge [2}] Appl Assistant ExaminerRonald B. Cox

Att0mey-Holman & Stern [30] Foreign Application Priority Data Mar. 18, 1970 Great Britain ..l2,927/7O [57] ABSTRACT A liquid fuel pumping apparatus including a shuttle [52] US. Cl. ..123/139 BD, 123/140 MP, 123/140 R, the excursion of which determines the maximum 417/295 quantity of fuel which can be supplied to an engine, [51] Int. Cl. ..F02m 39/00, F02d 1/04 the extent of outward movement of the shuttle being [58] Field of Search 123/139 AW, 139 BD, omitted by a stop in the form of a piece having a con- 123/140 MP, 140 CC; 417/295, 298 toured surface, the stop being mounted in a fluid pressure operable piston. The position of the piston de- [56] References Cited pends upon the speed at which the apparatus is driven. In addition the setting of the piece is determined by UNKTED STATES PATENTS axially movable member the axial position of which is 3,354,876 11/1967 Durham ..123 140 MP determined by a diaphragm to which is applied air 3,046,963 7/1962 Bessiere ..l23/ 139 BD under pressure from the inlet manifold of the as- 3,368,490 2/ 1968 Virello ..417/295 sociated engine, 2,465,784 3/1949 Berlyn ....4l7/295 2,297,234 9/1942 Meiswinkel ..4l9/295 4 Claims, 3 Drawing Figures Z0 Z1 10 22 A4 L 4 5Z 55 M 500. 46 =iil n I I 1 x71\\\ 1\ \\1 68 so 56 43 47 5| 53 54 PATENT U MR1 0 1373 SHEET 2 UF 2 ATTORNEYS m mm W M LIQUID FUEL PUMPING APPARATUS This invention relates to liquid fuel pumping apparatus for supplying fuel to internal combustion engines and of the kind including a shuttle the allowed excursion of which in a cylinder determines the maximum quantity of fuel which will be supplied by the apparatus to an associated engine, a piston slidable within a cylinder, the position of the piston being dependant upon the speed at which the associated engine is driven, an adjustable piece supported within the piston and having a contoured surface presented towards the shuttle whereby as the piston moves the allowed excursion of the shuttle will vary.

The object of the invention is to provide such an apparatus in a simple and convenient form and in which adjustment of the excursion of the shuttle can be effected in accordance with the air pressure existing in the inlet manifold of the associated engine.

According to the invention, an apparatus of the kind specified is characterized in that there is engaged with the piece on the side thereof removed from the shuttle one end of a slidable pin, said pin bearing at its other end, upon the contoured surface of a slidable member, pressure responsive means being provided to effect adjustment of the member in accordance with the pressure existing in the inlet manifold of the engine.

One example of a liquid fuel pumping apparatus in accordance with the invention will now be described with reference to the accompanying drawings in which:

FIG. 1 shows in sectional side elevation, a known form of apparatus,

FIG. 2 is a section on the line 2-2 of FIG. 1, and

FIG. 3 the modification necessary to the apparatus of FIGS. 1 and 2 in accordance with the invention.

Referring to FIGS. 1 and 2 of the drawings there is provided a body part in whichthere is mounted a rotary cylindrical distributor 11 which is adapted to be driven in timed relationship with anassociated engine. At one end of the distributor there is located an injection pump including a. pair of pumping plungers 12 which are disposed within a transversely extending bore 13 formed in the distributor.

Surrounding this end of the distributor is a cam ring 14 having formed on its internal periphery, a plurality of pairs of carns. Intermediate the plungers respectively and the cam ring are a pair of rollers 15 which bear upon the cam ring so that as the distributor rotates inward movement will be imparted to the plungers as the rollers ride over the-cams. Intermediate the plungers the bore defines a fuel pumping chamber which is in communication with a longitudinal passage 16 formed in the distributor.

At one point the passage 16 is in communication with a radially disposed delivery passage 17 which is arranged to register in turn as the distributor rotates, with a plurality of outlet passages 18 formed in the body part. This registration of the delivery passage with an outlet passage takes place during the whole of the time the plungers 12 are moving inwardly and the arrangement is such that fuel will be displaced from the pumping chamber to the outlet passage 18 in turn. The outlet passages are in use, connected to injection nozzles respectively mounted so as to direct fuel into the combustion spaces of the associated engine.

At another point the longitudinal passage 16 is in communication with a plurality of radially disposed inlet passages 19 formed in the distributor and which can communicate in turn with an inlet port 20 formed in the body part. This communication takes place whilst the delivery passage 17 is out of register with the outlet passages 18 and during this time fuel flows from the inlet port 20 to the pumping chamber of the injection pump to provide a fresh charge of fuel for the next injection stroke of the injection pump. The inlet port is in constant communication with one end of a cylinder 21 formed in the body part and mounted within the cylinder is a cylindrical and axially movable shuttle 22.

Also provided is a vane type feed pump 23 the rotor of which is formed integrally with the distributor at the end thereof remote from the transverse bore. The feed pump is provided with an inlet 24 which in use, is connected to a reservoir of fuel, and in addition the feed pump has an outlet 25. Moreover, the outlet pressure of the feed pump is controlled by any convenient valve so that it varies in a manner dependant upon the speed at which the distributor and hence the engine rotates.

The outlet 25 of the feed pump is in communication with a circumferential groove 26 formed in the periphery of the distributor and this is additionally in known manner and the throttle member functions by varying the effective size of a port 28 formed in the wall of the cavity. This port is in communication with a further circumferential groove 29 formed in the periphery of the distributor. From the groove 29 extend a plurality of longitudinal grooves 30 and these are of a length so that they can register with the inlet port 20 and are alternately arranged with the passages 19.

When one of the grooves 30 registers with the inlet port 20 fuel flows into the cylinder 21 and the shuttle 22 is moved outwardly. During the outward movement of the shuttle 22 fuel flows from the end of the cylinder 21 remote from the inlet port, by way of a passage 31 and grooves 32 formed in the periphery of the distributor member to a drain space located within the apparatus. Surplus fuel from this space can leave the apparatus by way of an outlet 33. As the distributor rotates one of the inlet passages 19 moves into register with the inlet port 20 and fuel under pressure from the outlet 25 of the feed pump flows to the end of the cylinder 21 remote from the inlet port, by way of a passage 34 and the grooves 35 on the distributor. The latter grooves extend from the circumferential groove 26. The pressure of fuel moves the shuttle 22 towards the inlet port and the previously throttled quantity of fuel is displaced through the pumping space of the injection pump.

In order to limit the maximum quantity of fuel which can be supplied to the engine, a stop is provided to limit the excursion of the shuttle 22 away from the inlet port 20. It has been found that it is desirable to vary the maximum quantity of fuel which can be supplied to the engine in a manner which depends upon the speed of the engine and for this purpose the stop takes the form of a fluid pressure operable piston 36 which is accommodated and movable within a cylindrical chamber 37 disposed substantially at right angles to the longitudinal axis of the cylinder 21 containing the shuttle. The piston is loaded towards one end of the chamber by coiled compression springs 38 and is movable against the action of the springs by fuel under pressure from the outlet 25 of the feed pump which is supplied to one end of the chamber through a passage 39. Fuel leaves the other end of the chamber by way of a passage 40.

In the piston 36 there is formed a transverse bore in which is mounted a piece 41 which can be moved relative to the piston in a direction substantially parallel to the axis of the cylinder 21 but which is fixed against angular movement by a pin which slides within a groove formed in the wall of the bore. The end surface of the piece 41 and which is presented to the shuttle is suitably shaped so that for instance as the piston 36 is moved against the action of its springs the permitted movement of the shuttle away from the inlet port is reduced. The other end of the piece 41 bears against a flat head of an adjusting screw 42 which can be adjusted from the exterior of the apparatus, so that during movement of the piston no relative movement of the piece relative to the piston occurs. By this means the maximum quantity of fuel which can be supplied to the engine is controlled and moreover by altering the setting of the adjusting screw 42 the apparatus can be adjusted quickly to suit a particular engine or a particular type of engine. In addition when manufacturing the apparatus it is only necessary to produce a range of such pieces 41 to enable the apparatus to be used to supply fuel to different types of engine.

The surface 43 of the piece 41 is provided with a recess 44 which enables an excess of fuel to be supplied to the engine for starting purposes.

In the case of an engine which is provided with a turbosupercharger it is essential to be able to adjust the maximum quantity of fuel which can be supplied to the engine in accordance with the pressure of air delivered by the turbosupercharger. With increasing air pressure the larger quantity of air will be admitted to the engine cylinders and therefore more fuel can be burnt.

In order to provide the desired adjustment the apparatus shown in FIGS. 1 and 2 is modified in accordance with FIG. 3. It will be noted that the adjusting screw 42 has been omitted.

There is mounted in the pump body a pin 45 which is slidable along the axis of movement of the shuttle 22. The pin 45 projects through an apertured bush 46 secured within the pump body and it engages at one end with the piece 41. At its other end the pin 45 engages with a contoured surface 47 formed upon an adjustable member 48 the axis of movement of which is at right angles to the axis of movement of the shuttle 22. The member 48 is mounted within a body portion 49 which is adapted to be secured to the pump body 10. The member 48 is loaded in one direction by means of a coiled compression spring 50 and in the rest position as is shown, the end of the member 48 abuts against a step 50a defined in the body 49.

The member 48 is provided with three lands 51 which guide the axial movement of the member and at the spring end of the member there are provided forks 52 engageable with complementary forks 53 formed on an angularly adjustable member 54. The member 54 is provided with a locking ring 55. In this manner angular adjustment of the member 54 will effect angular adjustment of the member 48. The surface 47 is of tapering cylindrical form and has its axis off set from the axis of the member 48 so that angular adjustment of the member will effect the initial setting of the pin 45, whilst the degree of taper of the surface fixes the variation in the setting of the pin 45 for a given movement of the member 48.

In order to move the member 48 against the action of its spring there is provided a rolling diaphragm 56 which is disposed between an internal cylindrical wall 57 defined in the body 49 and the external peripheral surface of a cup shaped member 58. The member 58 is mounted on a push rod 59 which contacts the member 48. Moreover, the end of the push rod 59 remote from the member 48 is provided with a screw thread for the reception of a complementarily threaded nut 60 and this acts to maintain the cup shaped member 58, the diaphragm 56 and and a locating plate 61 in position on the bush rod. The diaphragm 56 is sandwiched between the locating member 61 and the cup shaped member 58. In addition, a coiled compression spring 62 is provided to urge the push rod into contact with the member 48. The spring 62 is weaker than the spring 50 so that when the engine is at rest the member 48 contacts the step 50.

In order to effect movement of the diaphragm 56 there is provided an inlet 63 for connection to the inlet manifold of the associated engine. This engine is provided with a turbosupercharger so that the pressure within the inlet manifold will be higher than atmospheric pressure. The other side of the diaphragm is exposed to a lower pressure and conveniently this is the drain pressure of the fuel. There is provided an outlet 64 for connection for instance to the inlet of the feed pump and fuel leaking past the pin 45 will return to the inlet of the feed pump by way of the outlet.

In use, as the inlet manifold pressure increases the push rod 59 will be moved towards the right as seen in FIG. 3 and the contoured surface 47 on the member 48 will act as a stop, increasing movement towards the right allowing a larger excursion of the shuttle 22.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. A liquid fuel pumping apparatus for supplying fuel to internal combustion engines and compressing a cylinder, a shuttle movable within the cylinder, an injection pump to which fuel is supplied from the cylinder by movement of the shuttle therein, the maximum quantity of fuel which will be supplied by the apparatus being determined by the allowed excursion of the shuttle in the cylinder, a piston slidable within a further cylinder, means for altering the position of the piston in accordance with the speed of operation of the engine, an adjustable piece mounted within the piston, a contoured surface defined on said piece and presented to the shuttle, said surface constituting a stop for the shuttle whereby as the piston moves the allowed excursion of the shuttle will vary, the apparatus being characterized by a pin one end of which is engaged with the piece on the side thereof removed from the shuttle, a slidable member, said pin bearing at its other end, upon a contoured surface on the slidable member, and pressure responsive means to effect adjustment of the member in accordance with the pressure existing in the air inlet manifold of the engine.

2. An apparatus as claimed in claim 1 in which said pressure responsive means comprises a rolling diaphragm.

3. An apparatus as claimed in claim 2 in which said rolling diaphragm acts on said slidable member through the intermediary of a push rod, said push rod being loaded into contact with said slidable member by a first coiled compression spring, and the slidable member being loaded in the opposite direction by a second 

1. A liquid fuel pumping apparatus for supplying fuel to internal combustion engines and compressing a cylinder, a shuttle movable within the cylinder, an injection pump to which fuel is supplied from the cylinder by movement of the shuttle therein, the maximum quantity of fuel which will be supplied by the apparatus being determined by the allowed excursion of the shuttle in the cylinder, a piston slidable within a further cylinder, means for altering the position of the piston in accordance with the speed of operation of the engine, an adjustable piece mounted within the piston, a contoured surface defined on said piece and presented to the shuttle, said surface constituting a stop for the shuttle whereby as the piston moves the allowed excursion of the shuttle will vary, the apparatus being characterized by a pin one end of which is engaged with the piece on the side thereof removed from the shuttle, a slidable member, said pin bearing at its other end, upon a contoured surface on the slidable member, and pressure responsive means to effect adjustment of the member in accordance with the pressure existing in the air inlet manifold of the engine.
 2. An apparatus as claimed in claim 1 in which said pressure responsive means comprises a rolling diaphragm.
 3. An apparatus as claimed in claim 2 in which said rolling diaphragm acts on said slidable member through the intermediary of a push rod, said push rod being loaded into contact with said slidable member by a first coiled compression spring, and the slidable member being loaded in the opposite direction by a second coiled compression spring, said second coiled compression spring being stronger than said first spring.
 4. An apparatus as claimed in claim 3 in which said slidable member is of cylindrical form, the contoured surface on said slidable member being of tapered cylindrical form, having its axis offset from the axis of the slidable member, means being provided to adjust the angular setting of said member. 